1. Field of Invention
The present invention relates to a method for manufacturing an organic electro-luminescent display. More particularly, the present invention relates to a method for manufacturing a control element of an organic electro-luminescent display.
2. Description of Related Art
Organic electro-luminescent displays have the advantages of low cost, long life, low driving voltage, high reaction speed, effective lighting, excellent temperature difference endurance, excellent vibration endurance, wide viewing angle and dimensional thinness. Many manufactures have spent great effort and resources researching and developing organic electro-luminescent displays. Thus, organic electro-luminescent displays may replace thin film transistor liquid crystal displays in the coming years.
Reference is made to FIGS. 1A˜1E, which are cross-sectional views showing a traditional method for manufacturing a control element of an organic electro-luminescent display. In FIG. 1A, a first gate electrode 122 of a first transistor, a bottom electrode 124 of a capacitor and a second gate electrode 126 of a second transistor are formed on an insulating substrate 110.
In FIG. 1B, a dielectric layer 130 is formed over the first gate electrode 122, the bottom electrode 124 of the capacitor and the second gate electrode 126 as a gate dielectric of the first transistor and the second transistor and a dielectric layer of the capacitor. Then, a first channel 142 of the first transistor and a second channel 146 of the second transistor are formed over parts of the first gate electrode 122 and the second gate electrode 126.
In FIG. 1C, an etching stop layer 150 is formed. The etching stop layer 150 is positioned over part of the first gate electrode 122 and the second gate electrode 126 for preventing influence from subsequent processes.
In FIG. 1D, a doped semiconductor layer 160 is formed over the insulating substrate 110. Then, the doped semiconductor layer 160 and the dielectric layer 130 are patterned and a hole 180 is formed to expose portion of the second gate electrode 126. The source/drain junctions of the first transistor and the second transistor are formed in this step.
In FIG. 1E, a conductor layer 170 is formed over the insulating substrate 110 and in the hole 180. Then, the conductor layer 170 is patterned for forming the source/drain electrode of the first transistor, the second transistor and a conducting wire. The conducting wire electrically connects the drain of the first transistor, the upper electrode of the capacitor, and the second gate electrode 126.
The etching stop layer and the hole are formed separately in the traditional method for manufacturing a control element of an organic electro-luminescent display. This may increase the amount of steps comprised by the traditional method such that the cost of the organic electro-luminescent display is increased and the yield of the organic electro-luminescent display is decreased.
Moreover, the dielectric layer of the capacitor and the gate dielectric of the first transistor and the second transistor are formed in the same step in the traditional method for manufacturing a control element of an organic electro-luminescent display. Thus, the electrical and geometric characteristics of the first transistor and the second transistor change if the capacitance of the capacitor is changed, such that the design of the control element of the organic electro-luminescent display is limited.
For the foregoing reasons, there is a need for a manufacturing method of a control element of an organic electro-luminescent display, which enables reducing the steps of the method and relaxes the design limitation.